This invention relates to the handling of cartons which have an ultra-low friction outer surface, such as cartons of consumer products and the like.
More and more commonly, consumer products such as soap powders, breakfast cereals, beverages and the like are packaged in containers having a vividly printed graphic outer surface, to provide advertising and to attract consumers' attention at points of sale. This trend toward high visibility graphics minimizes the need for display ads in self-service stores because the packages themselves function to present information in up to seven colors. Moreover, new retailing entities, such as the so-called club stores or discount stores, which are increasing in popularity, find they can sell more merchandise if is displayed in highly visible, eyecatching packaging.
The demand for more attractive containers has revolutionized the packaging surface itself so that it is more receptive to the new panoply of high visibility inks, graphics, and even hologram displays. All of these surfaces require a glossy overprint varnish which enhances the attractive presentation and maintains the integrity of the package graphics during filling, transportation and handling of the containers in general. Almost without exception, these high gloss overcoats produce ultra-low friction surfaces which are extremely slick or slippery. In fact, in the absence of these very low friction surfaces, the packages would rub together and thereby abrade and distort or destroy the graphic presentation. Also, with the high speed filling equipment currently in use, less slippery container surfaces tend to cause jam-ups, slow-downs and other undesirable production problems.
For all of the foregoing reasons, and others, this demand for ultra-low friction packaging surfaces will undoubtedly intensify with time. However, the very slipperiness of the product containers presents particular problems with respect to transporting the merchandise from manufacturer to wholesaler to retailer, and ultimately to display areas for the consumer in the store.
Due, at least in part, to their high gloss outer surfaces, it is generally difficult to directly palletize the product packages for transfer through the merchandise chain. Therefore, the individual cartons are commonly packed batchwise in containers or boxes which may themselves be more readily palletized. The boxes, generally made of corrugated paper or cardboard inherently have a higher coefficient of friction than the high gloss cartons and are, therefore, more readily handled and transported. Sometimes, even the cardboard boxes are treated with a heavy coating of a normal or conventional nonskid material, such as colloidal silica or alumina, to increase their frictional properties, and, thereby, facilitate palletizing the boxes for handling and transportation.
The use of such corrugated cardboard boxes obviously increases the cost of merchandising the product. For example, one must consider the cost of the boxes themselves, as well as the economic and environmental costs of recycling or destroying the boxes after use. Further, the labor and equipment costs in packing and unpacking the boxes exceeds the cost of the boxes themselves by many times. Such costs are undesirable, at best. In certain instances, such as in the club stores where prices are discounted and profit margins are limited to start with, these additional costs can become totally unacceptable.
Various concepts have been tried to minimize these problems. Packing boxes have been devised with almost "picture frame" sides, so that the inner contents are visible. Half-height trays have been used to facilitate displaying the high gloss merchandise. These "solutions" present their own obvious problems.
Entire pallets of individual product cartons have been stabilized for shipping by overwrapping horizontally with multiple turns of thin plastic film material such as stretch wrap. This approach effectively cocoons the cartons and avoids the needs for packing and unpacking cardboard boxes. However, palletized product cartons wrapped in this manner are still highly unstable and difficult to transport without carton movement. With high gloss product cartons, the instability of the pallet is such that simply transferring the stacked cartons to the stretch wrapper causes the cartons to slide relative to each other. Moreover, removing the stretch wrap, or attempting to move the pallet by a conventional fork lift truck from the receiving area in a club store or the like, to the merchandising floor for display once the stretch wrap has been removed, will also disrupt and destroy the stack. Therefore, further handling of the product cartons, either by individually placing them on shelves, or restacking them in some other fashion for display, becomes necessary.
The use of paper sheets between the layers of a pallet to help stabilize the pallet is a well-established, but infrequently used, practice. These sheets are variously known as tier sheets or tie sheets, or slip sheets in the case of one on the bottom for full pallet handling. They can be made of light to heavy weight kraft paper, or recycled chipboard sheets of various calipers, from 0.010 to 0.030 inches, depending on costs and conditions of use. In some rare instances, these pallet-sized sheets have had a conventional non-skid, such as colloidal alumina or silica, applied to one side to impart a modicum of slip resistance. The benefit, however, is usually minimal and in the instant case, with glossy, high graphic cartons, usually of no apparent benefit in handling.